Existential risk is a threat to human survival, or to the long-term potential of our species.  存在风险是对人类生存，或对整个人类种群的长远潜能的一种威胁。

　　Now, why do I say that this is a big problem?  为什么我会认为这是一个重大问题？

　　Well, let's first look at the probability --  让我们来看看可能性——

　　and this is very, very difficult to estimate  这非常难估量

　　but there have been only four studies on this in recent years, which is surprising. 但近年来，这个领域只出现了四篇研究文章，这很让人吃惊。

　　You would think that it would be of some interest  你可能会认为，既然厉害关系如此巨大，

　　to try to find out more about this given that the stakes are so big,  那么在这个领域做研究一定是有意义的。

　　but it's a very neglected area.  然而，这是一个被人们忽视的领域。

　　But there have been four studies -- one by John Lesley, wrote a book on this. 但是，已经有了四篇研究——其中一篇由约翰·雷斯利所著，为这个问题写了一本书。

　　He estimated a probability that we will fail to survive the current century: 50 percent. 据他估计，有50%的可能性我们会在这个世纪灭亡。

　　Similarly, the Astronomer Royal, whom we heard speak yesterday,  类似的，皇家天文学家--我们昨天听过他的演讲--

　　also has a 50 percent probability estimate.  的估算结果也是50%。

　　Another author doesn't give any numerical estimate,  另外一个作者并没有给出任何数据估算，

　　but says the probability is significant that it will fail.  但他指出，人类灭亡的可能性非常高。

　　I wrote a long paper on this.  我就这个问题写了一篇长篇论文

　　I said assigning a less than 20 percent probability would be a mistake in light of the current evidence we have. 我在文章里指出，根据现有的证据，任何低于20%的可能性估算都应该是错误的。

　　Now, the exact figures here, we should take with a big grain of salt, 对于这里的具体数字，我们不应该全盘相信，

　　but there seems to be a consensus that the risk is substantial.  但人们似乎对此达成共识，风险的确不小。

　　Everybody who has looked at this and studied it agrees.  每个看过并研究过这方面的人，都会同意。

　　Now, if we think about what just reducing  那么，如果我们考虑

　　the probability of human extinction by just one percentage point, not very much 将人类灭绝的可能性几率只减少一个百分点，并不是很多

　　so that's equivalent to 60 million lives saved,  那就相当于拯救了六千万的生命，

　　if we just count the currently living people, the current generation.  而这只是计算现存的人类，当代人口。

　　Now one percent of six billion people is equivalent to 60 million.  那么六十亿人的百分之一相当于六千万。

　　So that's a large number.  这是一个很大的数字。

　　If we were to take into account future generations  如果我们把未来的人口也算进来

　　that will never come into existence if we blow ourselves up,  如果我们把自己毁灭了，未来人口也永不会存在，

　　then the figure becomes astronomical.  那么这数字就变成天文数字了。

　　If we could eventually colonize a chunk of the universe -- the Virgo supercluster -- 如果我们最终可以开拓宇宙的一角为生存地，比如室女座超星系团

　　maybe it will take us 100 million years to get there,  可能我们需要一亿年才能到达那儿，

　　but if we go extinct we never will.  但如果我们灭亡了，我们永远也到不了

　　Then, even a one percentage point reduction in the extinction risk 那么，即使是减少百分之一的灭绝风险，

　　could be equivalent to this astronomical number -- 10 to the power of 32. 那将等同于这个极为庞大的数字——10的32次方。

　　So if you take into account future generations as much as our own,  那么，如果你像关心我们自己一样关心我们的后代，

　　every other moral imperative of philanthropic cost just becomes irrelevant.  所有其他基于道义责任的慈善都变得无关紧要。

　　The only thing you should focus on would be to reduce existential risk 你所应该关注的唯一事情就是减少生存风险

　　because even the tiniest decrease in existential risk  因为即使只减少极少的一点生存风险，

　　would just overwhelm any other benefit you could hope to achieve.  其带来的好处也可以覆盖其它任何你希望获得的利益。

　　And even if you just look at the current people,  另外，如果你仅仅关注现在的人类，

　　and ignore the potential that would be lost if we went extinct,  而忽略那些一旦我们灭绝后可能失去的潜能，

　　it should still have a high priority.  减少存在风险也仍旧值得优先考虑。